Rat ventral prostates are mechanically dissociated and fractions enriched in epithelial and connective tissue cells isolated by centrifugation on Ficoll gradients. Cells from various hormonally-manipulated prostates are co-cultivated with the aim of determining factors required for their growth and the nature of interactions between epithelium and connective tissue cells. As part of this study, we observed a C-type RNA virus associated with epithelial but not with connective tissue cells, and the biology of this virus is under study. In addition, a Chinese hamster ovary cell line with a temperature-sensitive defect in cytoplasmic non-mitochondrial protein synthesis is being used to examine protein synthesis intrinsic to cell nuclei.